Arcs will only be output in the CNC code where the original vector geometry includes arcs and lines.
Where a design is constructed from Bezier curves the toolpath will be G1 point to point moves.
It is possible to convert Bezier curves to Arcs using the Node Editing Tools that are available
off the Right mouse menu, or a much quicker method is to use the keyboard shortcuts,
N - Node Edit
I – Insert Point (often need to insert intermediate points to maintain the shape)
A – Convert span to Arc
This is can be a time consuming process but sometimes worth the effort.
I hope this helps,